System and method for avoiding stall using timer for high-speed downlink packet access system

Abstract

At least one timer is used to prevent a stall condition. If a timer is not active, the timer is started for a data block that is correctly received. The data block has a sequence number higher than a sequence number of another data block that was first expected to be received. When the timer is stopped or expires, all correctly received data blocks among data blocks up to and including a data block having a sequence number that is immediately before the sequence number of the data block for which the timer was started is delivered to a higher layer. Further, all correctly received data blocks up to a first missing data block, including the data block for which the timer was started, is delivered to the higher layer.

1. A method of controlling a stall avoidance in a reordering buffer of a communication device using at least one timer comprising:
 (a) receiving a plurality of MAC-hs PDUs by the reordering buffer of a MAC-hs sub-layer of a medium access control (MAC) layer; 
 (b) placing each MAC-hs PDU in the reordering buffer at a place indicated by each transmission sequence number (TSN) of each MAC-hs PDU; 
 (c) starting the at least one timer when a MAC-hs PDU is correctly received and the TSN of the MAC-hs PDU is higher than the next expected TSN if the at least one timer is not active, 
 (d) delivering to a higher entity all correctly received MAC-hs PDUs up to and including TSN-1 and all correctly received MAC-hs PDUs up to the next not received MAC-hs PDU when the at least one timer expires; and 
 (e) starting the at least one timer for a MAC-hs PDU having the highest TSN among those of the MAC-hs PDUs that can not be delivered to the higher entity. 
 
     
     
       2. The method of  claim 1 , wherein only one timer is allowed to be active at a given time. 
     
     
       3. The method of  claim 1 , wherein the at least one timer is stopped when the MAC-hs PDU which was correctly received and which had the TSN greater than the next expected TSN can be delivered to the higher entity before the at least one timer expires. 
     
     
       4. The method of  claim 1 , wherein the communication device is a mobile terminal. 
     
     
       5. The method of  claim 1 , wherein the communication device is a UMTS terrestrial radio access network (UTRAN). 
     
     
       6. The method of  claim 5 , wherein the UTRAN includes at least one node B. 
     
     
       7. The method of  claim 1 , wherein the higher entity includes a MAC-d sub-layer. 
     
     
       8. The method of  claim 1 , wherein the higher entity includes a radio link control (RLC) layer. 
     
     
       9. The method of  claim 1 , wherein there exists only one timer per reordering buffer. 
     
     
       10. The method of  claim 1 , wherein the communication device is a node B. 
     
     
       11. The method of  claim 1 , wherein a period of the at least one timer is less than or equal to N*(TTI/2), wherein N is the range of transmission sequence numbers to be assigned to the MAC-hs PDUs, and TTI is the transmission time interval. 
     
     
       12. An apparatus for controlling stall avoidance, the apparatus comprising:
 a reordering buffer configured to receive a plurality of MAC-hs PDUs and configured to place each MAC-hs PDU in the reordering buffer at a place indicated by each transmission sequence number (TSN) of each MAC-hs PDU; 
 at least one timer, wherein if the at least one timer is not active, the at least one timer is configured to start when a MAC-hs PDU is correctly received and the TSN of the MAC-hs PDU is higher than the next expected TSN; and 
 a medium access control entity connected with the reordering buffer and the timer, the medium access control entity adapted to, 
 deliver to a higher entity all correctly received MAC-hs PDUs up to and including TSN-1 and all correctly received MAC-hs PDUs up to the next not received MAC-hs PDU when the at least one timer expires; and 
 start the at least one timer for a MAC-hs PDU having the highest TSN among those of the MAC-hs PDUs that can not be delivered to the higher entity. 
 
     
     
       13. The apparatus of  claim 12 , wherein only one timer is allowed to be active at a given time. 
     
     
       14. The apparatus of  claim 12 , wherein the at least one timer is stopped when the MAC-hs PDU which was correctly received and which had the TSN greater than the next expected TSN can be delivered to the higher entity before the at least one timer expires. 
     
     
       15. The apparatus of  claim 12 , wherein the apparatus is implemented in a mobile terminal. 
     
     
       16. The apparatus of  claim 12 , wherein the apparatus is implemented in a UMTS terrestrial radio access network (UTRAN). 
     
     
       17. The apparatus of  claim 16 , wherein the UTRAN includes at least one node B. 
     
     
       18. The apparatus of  claim 12 , wherein the higher entity includes a MAC-d sub-layer. 
     
     
       19. The apparatus of  claim 12 , wherein the higher entity includes a radio link control (RLC) layer. 
     
     
       20. The apparatus of  claim 12 , wherein there exists only one timer per reordering buffer. 
     
     
       21. The apparatus of  claim 12 , wherein the apparatus is implemented in a node B. 
     
     
       22. The apparatus of  claim 12 , wherein a period of the at least one timer is less than or equal to N*(TTI/2), wherein N is the range of transmission sequence numbers to be assigned to the MAC-hs PDUs, and ITT is the transmission time interval.